This is a deck I created to auto-duel L45 standard duelists to win quickly and hopefully get 2-4 chests. Did a lot of tweaking over a couple of days when I'd lose a duel and this is the end result with what cards I have available. BC would be a lot better than SOrb.

Video of the deck in action:
https://www.youtube.com/watch?v=dDlzzeDlssQ

Note:
I did swap out the third Koala for B.E.S. Big Core basically for an easy tribute and protection while I get the fusion together.
I also pulled 3 fusions and 3 koalas after the video so I felt I needed an easy tribute that could survive a couple turns.

The rng never been kind to me whenever I face the THTD dexk. The rest is relatively easy using my Blue Eyes deck. Quick summoning a high level mon is the key. Also stuff your deck with spell and trap that can be use to negate opponent's trap and/or spell.

Focus on summoning Monster of Oz as early on in the duel as you possibly can (always pick any fusion related card if Crystal Seer lets you). If you don't get Oz right away, use Nutrient Z, Enchanted Javelin, Windstorm and Apophis to stall, and Golden Apples in defense position at the right time on their strongest monsters (which should be obvious if you've played them a few times), to make epic stall. When you summon Oz, none of these duelists can do a thing. They just sit there and burn turns. Deck out and Piranha Army combo your way to a reliable 6k score.